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SPECIES ASSESSMENT FOR BLACK-TAILED PRAIRIE DOG

(CYNOMYS LUDOVICIANUS) IN WYOMING

prepared by

REBECCA S. BUSECK1, DOUGLAS A. KEINATH

1 AND ERIC EVERETT

2

1

Wyoming Natural Diversity Database, University of Wyoming, 1000 E. University Ave, Dept. 3381, Laramie,

Wyoming 82071; 307-766-3023 2 Wyoming Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming

prepared for

United States Department of the Interior

Bureau of Land Management

Wyoming State Office

Cheyenne, Wyoming

February 2005

Buseck, Keinath, and Everett – Cynomys ludovicianus February 2005

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Table of Contents

INTRODUCTION ................................................................................................................................. 3

NATURAL HISTORY........................................................................................................................... 4 Morphological Description ...................................................................................................... 4 Taxonomy and Distribution ..................................................................................................... 5

Taxonomy ....................................................................................................................................... 5 Distribution ..................................................................................................................................... 5

Habitat Requirements............................................................................................................. 6 General ............................................................................................................................................ 6 Area Requirements.......................................................................................................................... 8 Landscape Pattern ........................................................................................................................... 8

Movement and Activity Patterns ............................................................................................. 9 Dispersal.......................................................................................................................................... 9 Activity Patterns............................................................................................................................ 10

Reproduction and Survivorship..............................................................................................10 Breeding Behavior......................................................................................................................... 10 Breeding Phenology ...................................................................................................................... 11 Fecundity and Survivorship .......................................................................................................... 11

Population Demographics......................................................................................................12 Metapopulation Dynamics ............................................................................................................ 12 Genetic Concerns .......................................................................................................................... 13

Food Habits ...........................................................................................................................13 Community Ecology...............................................................................................................15

CONSERVATION .............................................................................................................................. 16 Conservation Status ..............................................................................................................16

Federal Endangered Species Act................................................................................................... 16 Bureau of Land Management ........................................................................................................ 18 Forest Service................................................................................................................................ 18 State Wildlife Agencies................................................................................................................. 18 Heritage Ranks and WYNDD’s Wyoming Significance Rank..................................................... 19

Biological Conservation Issues ..............................................................................................21 Abundance and Abundance Trends............................................................................................... 21 Distribution and Connectivity Trends ........................................................................................... 22 Extrinsic Threats ........................................................................................................................... 23

Control Programs.................................................................................................................... 24 Recreational Shooting............................................................................................................. 25 Habitat Alterations.................................................................................................................. 26 Disease.................................................................................................................................... 27 Other ....................................................................................................................................... 29

Intrinsic Vulnerability ................................................................................................................... 29 Habitat Specificity and Fidelity .............................................................................................. 29 Territoriality and Area Requirements ..................................................................................... 30 Susceptibility to Disease......................................................................................................... 30 Dispersal Capability................................................................................................................ 31 Reproductive Capacity............................................................................................................ 32

Protected Areas ............................................................................................................................. 32 Population Viability Analyses (PVAs).......................................................................................... 33


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CONSERVATION ACTION ................................................................................................................ 33 Existing Conservation Plans ..................................................................................................33 Conservation Elements..........................................................................................................36

Acting on Conservation Elements................................................................................................. 37 Habitat Preservation and Restoration............................................................................................ 41

INFORMATION NEEDS ..................................................................................................................... 42

TABLES AND FIGURES ..................................................................................................................... 44 Table 1: Baily Eco-Region habitat model distributions for each state.......................................... 44 Table 2: Overview of C. ludovicianus status throughout its range. ............................................. 45 Table 3: Guidelines for C. ludovicianus habitat restoration and preservation ............................. 46 Figure 1: Photograph of adult and juvenile black-tailed prairie dog............................................. 47 Figure 2: Drawing of skull morphology of C. ludovicianus ......................................................... 48 Figure 3: North American range of all prairie dog species .......................................................... 49 Figure 4: Possible distribution of C. ludovicianus based on mixed-grass and short-grass prairie

distribution in eastern Wyoming ........................................................................................... 50 Figure 5: Rangewide distribution of the black-tailed prairie dog................................................. 51 Figure 6. Loop diagram depicting a) life cycle and b) related matrix model elasticities for female

black-tailed prairie dogs. ....................................................................................................... 52 Figure 7: Map of Natural Heritage Ranks for the black-tailed prairie dog. ................................. 53 Figure 8: Existing oil and gas developments in Wyoming........................................................... 54

LITERATURE CITED ........................................................................................................................ 55

ADDITIONAL REFERENCES ............................................................................................................. 61


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Introduction

Prairie dog colonies once stretched from southern Canada to northern Mexico, east of the

Rocky Mountains (Hall 1981). Prairie dogs affect many ecosystem processes (Detling and

Whicker 1987) and studies have suggested that prairie dogs are important for the maintenance of

biodiversity in grasslands (Miller et al. 1994, Reading and Matchett 1997), increasing species

richness or abundance of plants (Bonham and Lerwick 1976, Whicker and Detling 1988),

arthropods (Agnew et al. 1987), and vertebrates (Agnew et al. 1986, Barko 1996, Ceballos et al.

1999).

Historically, prairie dogs were the target of widespread eradication programs (Anderson et al.

1986, Miller et al. 1996), which, along with land conversion, led to decline of the species to less

than 2% of its original range, by conservative estimates (Miller et al. 1994, Mulhern and Knowles

1995). Competition between livestock and prairie dogs for forage has long been the justification

for eradication programs (Collins et al. 1984). However, O’Melia et al. (1982) found no

significant difference in weight gain between steers that grazed on or off prairie dog colonies. In

fact, facilitation in the form of enhancement of forage quality for, and preferential grazing by,

pronghorns (Krueger 1986), bison (Coppock et al. 1983b, Krueger 1986) and domestic cattle

(Knowles 1986) have been shown for prairie dog colonies relative to uncolonized mixed grass

prairie. Despite the obvious reduction in above-ground biomass available for grazers caused by

prairie dogs (Coppock et al. 1983a), ungulates seek out prairie dog colonies to forage (Whicker

and Detling 1988). The advantage to grazers comes in the form of enhanced crude protein

(nitrogen) content of the newly regrowing shoots of previously clipped vegetation (Detling and

Whicker 1987, Sharps and Uresk 1990). Likewise, prairie dogs may maintain an herbaceous cover

in grasslands and prevent encroachment of woody species, improving rangelands for other grazers

(Weltzin et al. 1997a, Weltzin et al. 1997b).


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Natural History

Morphological Description

Black-tailed prairie dogs (Cynomys ludovicianus) are robust, stockily built ground squirrels.

These animals are usually a buff brown with a grizzled black appearance (Figure 1). The last third

of the tail is black tipped and 7-10 cm long. Adult C. ludovicianus usually weigh 0.8-1.5kg and

reach a length of 31-41cm (including the tail; Clark and Stromberg 1987). The head is broad and

rounded with relatively large eyes and small ears. The legs are short and powerful, each foot

having 5 digits with well-developed claws for digging. The skull characteristics of black-tailed

prairie dogs are described by Hoogland (1996) and Hall (1981), but in general the skull is broad

and angular with large processes (Figure 2). Their body pelage molts seasonally (twice yearly;

Hoogland 1996) and is different between age and sex groups. The first to undergo the molt are the

non-breeding juveniles, second are the non-breeding adults, third are the breeding males, and last

are the breeding females (Hoogland 1995). It is thought that this sequence of molting is related to

the overall body condition, with the most “fit” individuals molting first (Hoogland 1995).

Juveniles undergo a “post-juvenile” molt starting at the rump and extending anteriorly (Smith

1967). Contrastingly, adults will molt posteriorly from the head every October. Males and females

will also exhibit a differential molt, with the genitalia and secondary sexual characters molting

soon after the head (Smith 1967). The color pattern on individual hairs differs during the

respective molt period (Hoogland 1996).

All five species of prairie dogs (see Taxonomy) are similar in morphology and appearance, but

since the species’ ranges do not overlap, locality is diagnostic (see below; Hoogland 1995).


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Taxonomy and Distribution

Taxonomy

The complete taxonomic classification for the black-tailed prairie dog is as follows (Hoogland

1996): Order: Rodentia, Suborder: Sciurognathi, Family: Sciuridae, Subfamily: Sciurinae, Tribe:

Cynomyini, Subtribe: Spermophilina, Genus: Cynomys, Subgenus: Cynomys, Species:

ludovicianus. Two subspecies of black-tailed prairie dogs are recognized: C. l. arizonensis located

in the southern portion of the black-tailed prairie dog range and C. l. ludovicianus located in the

northern part of the black-tailed prairie dog range (Hall 1981; Hoogland 1996). Black-tailed

prairie dogs are one of five species in the genus Cynomys, in the family Sciuridae. Mexican prairie

dogs (C. mexicanus) are the closest relative to black-tailed prairie dogs but do not overlap in

range. White tailed prairie dogs (C. leucurus) and Gunnison’s prairie dogs (C. gunnisoni) are

found in intermountain basins of the rocky mountain west (Clark 1987). Utah prairie dogs (C.

parvidens) are found in short-grass prairies of southwestern Utah and are more closely related to

white tailed prairie dogs (Hoogland 1996).

Interestingly, the prairie dog was originally named the “Louisiana marmot” (Arctomys

ludovicianus) by Ord in 1815 due to its outward resemblance to a marmot, but the name was

changed to the current genus Cynomys in 1817 by Rafinesque (Smith 1967).

Distribution

Black-tails are the most widely distributed species of prairie dog (Figure 3), thought to once

occur from southern Canada to northern Mexico, covering a continuous 400-mile wide band from

the foothills of the Rockies to the central lowlands of the Great Plains (Koford 1958, Hall 1981).

Currently, this species still occurs over its entire range (except Arizona) in small, fragmented

colonies (VanPutten and Miller 1999). Generally, C. ludovicianus occur east of the other four

prairie dogs in North America, occupying more mesic habitats.


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In Wyoming, the distribution of prairie dogs is restricted to the eastern third of the state,

where short and mixed grass prairies dominate the landscape (Figure 4). The western extent of this

range is not well defined, and there may be a zone of sympatry between C. ludovicianus and C.

leucurus, which occupy the sage-grassland basins in central and western Wyoming. There is only

one documented occurrence of a stable black-tailed prairie dog colony west of this area, in the

Bighorn Basin. Since this colony is so far from the main range of black-tails and is located along a

main highway, it likely represents an artificial, anthropogenic introduction rather than a legitimate

range expansion (D. Keinath, personal communication).

Recently the Wyoming Game and Fish Department (WGFD) in cooperation with the

Wyoming Bureau of Land Management (BLM) have completed a digital map of C. ludovicianus

towns in Wyoming using 2002 aerial photographs. The portion of this map that represents active

towns is unknown, since no estimate of activity has been assessed for the digitized towns. In

addition, the map is incomplete since 1/3 of the photographs were unable to be digitized. In fall

2005, the map should be available on the Wyoming Natural Diversity Database (WYNDD)

website (http://uwadmnweb.uwyo.edu/wyndd) after it has been evaluated and the quality of the

map can be reported (D. Keinath, personal communication).

Habitat Requirements

General

Black-tailed prairie dogs are thought to have once covered the entirety of the Great Plains

grasslands (Hall 1981, Miller et al. 1994) (Figure 5). Short- and mixed-grass prairies are easily

colonized by prairie dogs especially when the range is overgrazed or in poor condition (Koford

1958). Tall-grass prairie appears to be difficult for prairie dogs to inhabit (Allan and Osborn

1954), possibly because the high levels of vegetative production interfere with clipping, a behavior


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used by prairie dogs to lower overall vegetative height, facilitating predator detection. Fine, non-

sandy soils seem to be important for burrow construction (Clippinger 1989, Reading and Matchett

1997) and may influence the distribution of prairie dogs. Shrubby areas are less favorable for

colony establishment, but may not inhibit expansion of existing colonies (Weltzin et al. 1997a).

Gently sloping areas (0-10 degrees) are preferred and slopes over 20 degrees are rarely used in the

establishment of new colonies (Clippinger 1989, Reading and Matchett 1997). Cynomys

ludovicianus is rarely found above 2,377m and usually found below 1,829m (May 2004). Black-

tailed prairie dogs do not require open water (Clippinger 1989) because of a specialized kidney

physiology (Harlow and Menkens 1986) that allows them to more efficiently use water obtained

from plants. There is no seasonal variation in habitat requirements due to the colonial nature of

this species; therefore, the breeding, foraging, and over-wintering habitats are similar (Hoogland

1995).

A habitat suitability index (H.S.I.) model was completed in 1989 for black-tailed prairie dogs

by the USFWS (Clippinger 1989). Models, such as the one developed by Clippinger (1989), have

identified important habitat attributes for the species of interest. The habitat attributes considered

by Clippinger (1989) were availability of food, water, cover, and soil type. His conclusions about

food was that suitable habitat must contain sufficient grasses for spring and summer consumption,

a forb flora which will be utilized in fall, and adequate prickly pear available for water needs

during winter. According to Clippinger (1989), the food component of the H.S.I. model needs to

be a minimum of 15% herbaceous cover for continuous habitation by prairie dogs. For the cover

component, vegetative height levels of 5cm to 20cm are considered optimal with a slope of less

than 10 degrees for burrow establishment. The cover values are considered to be the most critical

component of the model by Clippinger (1989). Soil type is also considered, and has a broad


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spectrum of acceptable soil types for burrow establishment. Clippinger’s (1989) H.S.I. equation is

the following:

(V1 x V2 x V3 x V4 )¼

= H.S.I.

Where: V1= % herbaceous cover, V2= slope, V3= vegetative height, and V4= soil type

In Wyoming, short-grass prairies in the southeast along with mixed-grass prairies through the

northeast compose the majority of habitat for C. ludovicianus (Figure 4). The productive, gently

rolling hills of the eastern third of the state provide the necessary habitat for colony establishment.

The climate in Wyoming is favorable for year round activity, and provides a plant species

composition and productivity comparable to that of the nationwide range.

Area Requirements

Coteries, the smallest family unit of a colony or town, are on average 0.3 ha in size, but can

range from 0.05 ha to 1.0 ha in size (Hoogland 1995). In theory, the smallest possible unit of area

prairie dogs could colonize would be the area of land needed for one breeding pair or family unit

which would be ~ 0.05 ha. In Colorado, studies indicated that C. ludovicianus colony sizes ranged

from one acre to 4,129 acres, with an average size of 75acres; however, most colonies were 1 – 20

acres in size (see May 2004).

Landscape Pattern

The general landscape pattern needed for continous habitation of black tailed prairie dogs is

typified by the gently rolling topography and abundant forage of the Great Plains. Shrub

dominanted landscapes can also be colonized, but are less preferred to open habitats of grasses and

forbs (Clippinger 1989).


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Movement and Activity Patterns

Dispersal

The most common movement of this species is of minimal distance due to its colonial nature.

However, long distance dispersal does occur, but is very difficult to track (Hoogland 1995) and

seems to be rarely successful due to predation risk away from the colony. A study conducted on

intercolonial dispersal by Garrett and Franklin (1988) found that dispersal distances can be as

much as 5 km. They also found that prairie dogs rarely disperse to start a new colony, rather they

move to another established colony. The most common time for dispersal to occur is about a

month or so after the juveniles have emerged for the year (Hoogland 1995).

The ultimate cause of dispersal from the natal breeding sites is to prevent inbreeding

(Felhamer et al. 2004). Within C. ludovicianus populations, young males leave the family group

before breeding, whereas females remain. In addition, adult males usually leave groups before

their daughters mature (Hoogland 1982). Immigration and emigration by yearling males can be

important for gene flow (outbreeding) in large complexes of black-tailed prairie dogs if dispersal

is across mostly colonized area (Hoogland 1995).

Impediments to dispersal are largely centered on predation risk. Black-tailed prairie dogs

heavily rely on the alarm calling actions of nearby vigilant conspecifics (Hoogland 1981), and a

low degree of visual obstruction to detect danger. When venturing into uncolonized, unclipped

territory, the danger of predation increases (Hoogland 1995). As a result, most adult and some

juvenile male dispersal is within his home colony, although not near his home coterie. Long

distance dispersal, when it occurs, is most commonly associated with juvenile rather than adult

males, and is usually solitary rather than group movements. Male dispersal peaks during a

postweaning period (June – August; Roach et al. 2001). Dispersal of juvenile females is very

uncommon because they usually stay and breed on the home coterie for life. If dispersal does


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occur with a female prairie dog, it is almost always long distance dispersal to another established

colony (Hoogland 1995). Other barriers to movement are few, but include large bodies of water

such as wide rivers and large lakes.

Activity Patterns

Prairie dogs are diurnal, usually appearing above ground at dawn during the warmer months

and midmorning during the winter months. The heaviest above ground activity occurs between

7am and 11am and 5pm and 8 pm (Tileston and Lechleitner 1966, Biggins et al. 1993). Cynomys

ludovicianus may spend as much as 95% of their time above ground during the daylight hours, and

retreat into burrow for only 15-20 minutes to momentarily escape the heat (Hoogland 1995).

Black-tailed prairie dogs are not “obligate hibernators”; instead, they exhibit a state of

facultative torpor due to food shortage (in captivity) during the winter months (Harlow and

Menkens 1986) and/or weather (i.e., ambient temperature for free-ranging C. ludovicianus;

Lehmer et al. 2001, 2003). Free-ranging females demonstrated facultative aestivation in summer

months during periods of precipitation (Lehmer et al. 2003). Although C. ludovicianus

demonstrate facultative torpor, they can be active throughout the year (Hoogland 1995).

Facultative torpor is one area of prairie dog physiology and ecology that needs further study.

Reproduction and Survivorship

Breeding Behavior

Black-tailed prairie dogs exhibit a harem-polygynous mating system (Hoogland et al. 1987).

Usually, one breeding male, two to three adult females, and one or two yearlings of each sex make

up a territorial family group, or coterie, although as many as 26 prairie dogs may occupy the

largest of coteries (Hoogland 1995). Fierce protection of coteries by males can lead to combat

between males, but rarely leads to serious injury or death. Coterie size may vary from 0.05 to 1.1


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ha and will contain a variable number of burrows depending on the number of animals, especially

breeding females, on that coterie. Since prairie dog females usually stay on the natal coterie, this

species avoids inbreeding by four mechanisms: 1) male biased natal dispersal, 2) older males

disperse from coteries when daughters become sexually mature, 3) yearling females are unlikely to

come into estrus when their father is on the colony, and 4) behavioral avoidance of mating with

kin. These mechanisms are further explained in Hoogland (1995).

Breeding Phenology

The breeding season of black-tailed prairie dogs occurs between late January and early April

(Clark and Stromberg 1987) and lasts for 2-3 weeks (Smith 1967). Timing of copulation is

probably dependant on food availability and the severity of the preceding winter (Koford 1958,

Smith 1967). Black-tailed prairie dogs are generally synchronized breeders (Hoogland 1981),

breeding the same day in a coterie, and perhaps over 5 days throughout the colony (Hoogland

1995). Gestation is between 28 to 32 days (Smith 1967, Clark and Stromberg 1987). Altricial

young are usually born in the early spring and emerge from burrows at about 6 weeks of age. Pups

are fully grown in about 90 days (Clark and Stromberg 1987). Latitudinal differences in time of

breeding are also evident; for example, C. ludovicianus in Texas and Oklahoma breed in January,

in Colorado during February, and in Montana during March (Hoogland 1995, 1996).

Fecundity and Survivorship

Sexual maturity does not occur until 2 years of age (Smith 1967) differing from white tail

prairie dogs which mature and breed at 1 year of age. Garrett et al. (1982) found that the age of

first reproduction and pregnancy rate were both affected by the availability of food, and Knowles

(1987) found that litter size is directly connected to precipitation level of the preceding year.

Additionally, (Koford 1958) stated that breeding success is not necessarily depressed in small


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groups as it is in other social organisms like colonial nesting birds. An average litter size is 4

(Anthony and Foreman 1951) to 5 pups (Clark and Stromberg 1987) with the range occurring

between 2 and 8 (Hoogland et al. 1987).

Survivorship of male prairie dogs can be 3 or 4 years old and females usually live to be 5 or 6

years old (see Figure 6; Hoogland et al. 1987). Natal survivorship is unknown, but infanticide has

been documented and is considered the major cause of juvenile mortality within colonies

(Hoogland 1995, 1996). Juvenile survivorship does not appear to be as sex-biased as adult

survivorship with about 50% of each sex surviving their first year (Hoogland 1995).

Population Demographics

Metapopulation Dynamics

Although immigration and emigration to and from neighboring colonies is not important in

maintaining genetic diversity (see below), maintaining corridors between distinct colonies is

important for the long-term persistence of a metapopulation. A metapopulation can persist as long

as rate of recolonization (i.e., after events such as plague eliminates a colony) exceeds rate of

extinction. Increased isolation and disconnectivity of colonies will decrease successful dispersal

between colonies, increase genetic diversity between colonies, and may decrease genetic diversity

within isolated colonies through possible inbreeding and overall loss of alleles. Movement

between existing or unoccupied colonies is affected by physical aspects of the surrounding

landscape, such as tall grasses or urban and agricultural development. Maintaining corridors such

as drainages, roads, or trails could facilitate recolonization of unoccupied colonies and continual

dispersal among colonies (Roach et al. 2001).


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Genetic Concerns

Dobson et al. (2004) demonstrated that the polygynous mating system (coteries within

colonies) and female philopatry (see Dispersal below) of C. ludovicianus results in a strong

genetic differentiation of coteries within a colony. This genetic substructure within a colony has a

conserving influence on genetic diversity because different alleles predominate in different

coteries, and decrease the loss of genetic diversity of the entire colony. In fact, the genetic

diversity within a colony was influenced more from coteries within the colony than immigrants

(males) from neighboring colonies. Translocation of females (essentially increasing the female

dispersal rate) could actually increase the rate of inbreeding and loss of genetic variation by

bringing related males and females into spatial proximity (Sugg et al. 1996, Dobson et al. 2004).

This information should be considered when reintroducing or relocating C. ludovicianus to

different colonies.

Food Habits

Cynomys ludovicianus is herbivorous, consuming the stems, leaves, seeds, and roots of various

grasses, forbs, shrubs, and cacti. However, despite this breadth of food sources, black-tailed prairie

dogs are not considered opportunists (Uresk 1984), apparently selecting for specific species of

these growth forms. In fact, prairie dogs have been shown by Wydeven and Dahlgren (1982) and

Fagerstone et al. (1981) to choose plants that are not abundant on the range colonized. Unlike

other ground squirrels, and even other species of Cynomys, the black-tailed prairie dog does not

store food in its burrow (Koford 1958) or hibernate during the winter.

The first known food habit study (Kelso 1939) found that western wheat grass (Agropyron

smithii) and six-weeks fescue (Festuca octoflora) were most important followed by Russian thistle

(Salsola australus), prickly pear cactus (Opuntia spp.) and saltbush (Atriplex spp.). Uresk (1984)


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found that only four plant species composed 65% of the diet of black-tails in South Dakota, of

which grasses accounted for 87% of the diet and forbs composed 12%. Summers and Linder

(1978), as well as Fagerstone et al. (1981) and Wydeven and Dahlgren (1982) also found that

grasses are the most important component of prairie dog spring and summer diets, sometimes

composing up to 90% of the food eaten.

Much controversy has arisen on the food habits of prairie dogs due to the potential for

competition with domestic cattle (Uresk and Bjugstad 1983). However, steer weight gain on

pastures with and without prairie dog grazing were not statistically significant (O'Melia et al.

1982, Uresk and Bjugstad 1983). Further, preferred plant species overlap between cattle and

prairie dogs is not significant (Knowles 1986). Studies of the grazing relationship between bison

(Bison bison) (Coppock et al. 1983b, Krueger 1986), pronghorn (Krueger 1986), and cattle

(Knowles 1986) suggest that prairie dogs increase nutritional value of forage and change grazing

habits by increasing shoot nitrogen and reducing standing dead biomass (Detling and Whicker

1987).

Seasonal change in diet is very common and is thought to occur in response to the decreased

crude protein and increased fiber of mature plants (Fagerstone et al. 1981). Koford (1958) and

Fagerstone et al. (1981) found that during winter, basal parts of buffalograss (Buchloe

dactyloides), prickly pear cactus, fourwing saltbush (A.canescens), and rabbitbrush

(Chrysothamnus spp.) were important. Shallow digging for roots may also be an important source

of protein during winter (Tileston and Lechleitner 1966). During spring, the newly greening

vegetation is preferred and the dominant species consumed are Russian thistle, scarlet

globemallow (S. coccinea) and summercypress (K. scoparia). Shifts from C3 to C4 plants

throughout the summer may occur in response to the subsequent greening of these species. During


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fall, the green bases of grasses such as buffalograss and blue grama (Bouteloua gracilis) are

sought (Koford 1958, Fagerstone et al. 1981). Winter food items include mostly roots and prickly

pear cactus (Summers and Linder 1978, Wydeven and Dahlgren 1982). Interestingly, prairie dogs

have apparently developed the necessary physiology to cope with the oxalic acid occurring in

prickly pear, in order to gain its moisture rich benefit in the winter diet (Fagerstone et al. 1981). It

has been suggested that prairie dogs choose the most succulent form of vegetation available on a

seasonal basis due to water stress (Fagerstone et al. 1981). Grass may compose as much as 85% of

its wet weight as water (Hansson 1971), thus providing prairie dogs with the water needed for

efficient assimilation (Becksted 1977).

Community Ecology

The potentially disproportionate influence of black-tailed prairie dogs in prairie ecosystems

has led their being called keystone species, but this designation has been contentious (Stapp 1998;

Miller et al. 2000). Prairie dogs (Cynomys spp.) are important members of grassland communities.

They affect rangeland habitats by influencing plant species diversity and composition, creating

habitat preferred by other wildlife species (May 2004). An estimated 170 vertebrate species have

been alleged to rely on prairie dogs for some life needs (Clark et al. 1982; Reading and Matchett

1997; Lomolino and Smith 2003b). Well known obligates of prairie dog colonies include black-

footed ferrets (Mustela nigripes) (Biggins et al. 1985, Reading 1993) and burrowing owls (Athene

cunicularia) (Tyler 1968, Sharps and Uresk 1990), both of which depend on prairie dogs for

burrow structures and/or food.

Prairie dogs are thought to affect many ecosystem processes (Detling and Whicker 1987) and

habitat characteristics (Weltzin et al. 1997b), thereby having direct and indirect influences on the

flora and fauna around them. For example, the black-tail’s practice of “clipping” tall vegetation


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from burrow entrances to increase predator detection is similar to grazing and burning rangeland

practices that encourage new plant growth, which is more nutritional and palatable to other

wildlife species and domestic livestock (Knight 1994; May 2004). Removal of this species from

prairie ecosystems could have effects on plant and animal species diversity and abundance over

time. Lomolino and Smith (2003b) determined that C. ludovicianus towns harbored more rare and

imperiled species (i.e., swift fox, black-footed ferrets, and burrowing owls), and therefore a

decrease in prairie dogs could be detrimental to these species.

Conservation

Conservation Status

Federal Endangered Species Act

In 1998, two petitions were received by the U.S. Fish and Wildlife Service (USFWS) to list C.

ludovicianus as threatened under the Endangered Species Act of 1973 (ESA). One petition was

filed on July 30, 1998 by the National Wildlife Federation (NWF), and the second petition was

received on August 26, 1998 from the Biodiversity Legal Foundation, the Predator Project, and

Jon C. Sharps (see USFWS 2004b). These petitions listed several factors that could be major

threats to the viability and conservation of C. ludovicianus, including habitat loss, habitat

fragmentation, disease, unregulated shooting and poisoning, and the synergistic effects of these

threats and others. The 90-day finding for the petitions was published in the Federal Register (FR)

on March 25, 1999 (USFWS 1999) which stated that the petition action may be warranted. The

12-month finding by the USFWS on February 4, 2000 announced that listing C. ludovicianus was

warranted but precluded (USFWS 2000), and therefore considered a candidate for listing.


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Four of the five necessary conditions for listing were demonstrated (all were met except #2)

(VanPutten and Miller 1999). These conditions were:

1. Present of threatened destruction, modification, or curtailment of habitat.

This condition for listing was met by demonstrating the limiting of habitat, and

reduction of populations, that has occurred largely due to agricultural interests.

2. Over-utilization for commercial, recreational, scientific, or educational purposes.

This condition was not met. However, recreational shooting of prairie dogs may be

reinvestigated in the future, depending on regulation of this activity by agencies.

3. Disease or predation

This condition was met due to the high mortality (99.9%+) of prairie dogs faced with

sylvatic plague. Unfortunate epizootics could easily eliminate the population.

4. Inadequacy of existing regulatory mechanisms

This condition was met due to the classification of prairie dogs as pests in the states in

which they occur. Adequate management actions to curtail recreational shooting and

poisoning do not exist for many states.

5. Other natural or man-made factors affecting its continued existence.

This condition was met due to reasons in #4.

Candidate listing required reassessments and resubmitted petitions to be listed annually in the

FR (see USFWS 2001, USFWS 2002, USFWS 2004a). From these assessments and available

scientific and commercial information it was determined that the petitioned action to list C.

ludovicianus under the provisions of the Endangered Species Act (ESA) was not warranted on

August 18, 2004. As a result, C. ludovicianus is no longer considered a candidate for listing

(USFWS 2004b). The action to remove C. ludovicianus from the ESA candidate list was based on

the following determinations: 1) destruction of habitat from agricultural conversion and other

factors was no longer a threat, 2) modification of habitat due to the presence of plague was a

moderate, imminent threat, 3) the present limitation of habitat due to chemical control was no

longer a threat, 4) effects due to scientific or education purposes and commercial use of the


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species via the pet trade were not threats, 5) recreational shooting could be a low, imminent threat

in some circumstances, 6) predation was not a threat, 7) disease was a moderate imminent threat,

8) the inadequacy of existing regulatory mechanisms was a moderate, imminent threat, and 9)

chemical control and synergistic effects were moderate imminent threats (USFWS 2004b).

Bureau of Land Management

The State Offices of the Bureau of Land Management (BLM) in Montana, New Mexico, North

Dakota, South Dakota, and Wyoming list C. ludovicianus on their sensitive species lists.

According to the BLM Manual 6840, this designation is meant to provide protection of C.

ludovicianus and the habitat on which they depend. Therefore the BLM is responsible for

reviewing programs and activities on BLM land to determine their potential effect on C.

ludovicianus (USDOI BLM Wyoming 2001; Keinath et al. 2003).

Forest Service

The range of C. ludovicianus encompasses portions of four forest service regions: the central

part of the Northern Region (R1), the eastern half of the Rocky Mountain Region (R2), the eastern

portion of the Southwestern Region (R3), and the western portion of the Southern Region (R8).

Currently C. ludovicianus is listed as a sensitive species in Region 2

(http://www.fs.fed.us/r2/projects/scp/) and the subspecies, C. l. arizonensis is listed in Region 3

(New Mexico and Arizona; BISON 2004a).

State Wildlife Agencies

The Wyoming Game and Fish Department (WGFD) has developed a matrix of habitat and

population variables to determine the conservation priority of all species in the state. Seven

classes of Native Species Status (NSS) are recognized, with NSS1 representing critically imperiled

species and NSS7 representing stable or increasing species. Classes 1, 2, 3, and 4 are considered


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to be high priorities for conservation attention. The WGFD assigns C. ludovicianus a special

concern rank of NSS3. The NSS3 rank is based on WGFD estimates that C. ludovicianus

populations in Wyoming are declining or restricted in numbers and/or distribution and habitat is

restricted and/or vulnerable to human disturbance (Oakleaf et al. 2002; Keinath et al. 2003).

Oklahoma also recognizes C. ludovicianus as a special management concern. See Table 2 for a

complete list of state designations for C. ludovicianus across its range.

Heritage Ranks and WYNDD’s Wyoming Significance Rank

The Natural Heritage Network assigns range-wide and state-level ranks to species based on

established evaluation criteria (e.g., Keinath and Beauvais 2003, Keinath et al. 2003). Cynomys

ludovicianus merits a global rank of G3 (averaged), which means that when the range-wide

population is considered, it is deemed by Heritage scientists as rare or local throughout its range or

found locally in a restricted range. This is based on evidence that the extent of occupied habitat

and abundance has been reduced from its historic range (NatureServe 2004).

Twelve western states and provinces have assigned a State Rank to C. ludovicianus, none of

which rank it as demonstrably secure (Figure 7). In general, state ranks are assigned based on the

assessed risk of extinction within a state, where S1 species are deemed critically imperiled and S5

species are deemed demonstrably secure. These assessments are based on the biological

information on population status, natural history, and threats at the state level. Cynomys

ludovicianus is ranked as imperiled (S2) in New Mexico, Wyoming, and Saskatchewan;

vulnerable (S3) in Kansas, Montana, Oklahoma and Texas; and apparently secure (S4) in

Colorado, Nebraska and South Dakota. They are presumed extirpated (SX) in Arizona and their

status is under review in North Dakota (SU) (NatureServe Explorer 2004; Keinath et al. 2003,


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Keinath and Beauvais 2003). The black tailed prairie dog was ranked as imperiled in Wyoming

due to the following factors pertaining mainly to large towns (Keinath et al. 2003):

♦ Their range encompasses a moderate proportion (between 10% and 50%) of the state.

Their historic range in Wyoming likely covered about 40% of Wyoming (Clark and

Stromberg 1987). However, given fragmentation of habitat suggesting 0.01% of this

historic range being occupied (Table 1), prairie dogs may actually cover less than 240,000

acres, or 0.004% of the state (e.g., Luce 2001). Wyoming likely contains about 17% of

the historic black-tailed prairie dog range.

♦ They exhibit low range occupation (<20% of delineated range) and a patchy range-wide

distribution. Historic distribution touches several states, including Montana, Wyoming,

North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, New Mexico, Arizona,

and Colorado, but is quite patchy within this range.

♦ Their abundance within Wyoming is uncertain but probably declining (due to the intrinsic

vulnerabilities and external threats noted below). At the turn of the century, black-tailed

prairie dogs occupied more than 40 million acres, but estimates suggest less than 1% of

that area is currently occupied (Merriam 1902 as cited in Van Putten 1999; Van Putten and

Miller 1999). The area of occurrence is now very patchy (Mulhern and Knowles 1995). In

Wyoming about 0.01% of historically occupied land contains currently active colonies

(Luce 2001), which correlates to about 600,000 acres. However, estimates of active towns

are al low as 130,000 acres (Mulhern and Knowles 1995).

♦ They have high intrinsic vulnerability due to habitat specificity and susceptibility to

disease. Black-tailed prairie dogs are habitat specialists that occur mainly in flat, short and

mixed-grass prairies with fine, non-sandy soils (e.g., Hall 1981;Miller et al. 1994;

Clippinger 1989). Further, they are very susceptible to plague (Yersinia pestis), and

Wyoming seems to be experiencing a statewide epizootic as of summer 2001 (personal

communications with state land managers).

♦ They face high extrinsic threats, including active eradication programs, land conversion,

and habitat fragmentation. Poisoning, shooting, land conversion can each be a substantial

threat to black-tailed prairie dogs, but when combined they can devastate entire

populations beyond the point of recovery (e.g. Luce 2001; Gilpin 1999).


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The black-tailed prairie dog’s Wyoming Contribution Rank is “high,” because it is a native

resident with a moderate proportion of its otherwise restricted continental range in Wyoming.

Further, it has a restricted and patchy continental distribution and is arguably more secure in

Wyoming relative to other states (Keinath et al. 2003, Keinath and Beauvais 2003).

Biological Conservation Issues

Abundance and Abundance Trends

No good estimate of C. ludovicianus abundance across its range is available, although it is

estimated to be in the millions. Abundance of C. ludovicianus is generally expressed in terms of

surface area (hectares/acres) occupied by their colonies (Miller and Cully 2001), as it is more cost-

effective than surveying populations and calculating density. The USFWS believe that estimates

of occupied habitat provide the best available and most reasonable means of gauging populations

and status of the species across its range (USFWS 2004b). Ground-truthing exercises are

currently being carried out in New Mexico, Oklahoma, Texas, and Wyoming; therefore, a better

understanding of the accuracy obtained from using surface area occupied (obtained from aerial

surveys) to estimate abundance will be gained (Luce 2003; USFWS 2004b). Using recent

estimates of active C. ludovicianus acreage obtained from aerial and remote sensing surveys,

estimates of C. ludovicianus abundance was calculated by multiplying each acre by the typical

density of individuals per acre in colonies across its range (2 to 18 individuals per acre). From

these calculations the most current estimated abundance of C. ludovicianus is between 3,684,000

and 33,156,000 (average 18,420,000; USFWS 2004b). At the beginning of the 19th

century, C.

ludovicianus numbered near five billion (see BISON 2004b). Thus the abundance of black-tailed

prairie dogs has drastically decreased in the past century. It is estimated that C. ludovicianus has

been reduced across its western range by about 98 – 99% of its former abundance (Wuerthner

1997).


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In Wyoming, Mulhern and Knowles (1995) estimated that between 53,000 and 82,590 hectares

were occupied by black-tailed prairie dogs. Estimates from 2003 indicate that C. ludovicianus

occupy approximately 51,000 hectares, which conforms to the projected decline suggested by

Wyoming Game and Fish Department as a result of plague-infested colonies (USFWS 2004b). In

Wyoming, habitat loss or modification does not seem to be a large threat to C. ludovicianus

populations, since very little habitat has been lost within the past 30 years (i.e., only 25,000 acres

of rangeland converted to crops) and possible future land conversion is rather unlikely, since

Wyoming’s climate is not conducive to productive and economic crop growth (WBPDWG 2001).

Please refer to Table 1 for a state-by-state account of occupied acreage and Table 2 for population

trends throughout C. ludovicianus range.

Prior to 2003, most rangeland estimates of C. ludovicianus abundance were inconsistent and

based on imprecise and cursory information, such as limited aerial surveys, review of available

aerial photographs, and estimates from weed and pest control staff (Sidle et al. 2001; USFWS

2004b). These various methods provided incomplete and ad hoc data in order to determine

abundance trends. For more valid estimates, methodologies across C. ludovicianus range need to

be standardized. In addition, colonies need to be surveyed more regularly. Taking these actions

will not only provide a more accurate estimate of abundance, but will also help document changes

in populations as a result of plague, drought, and habitat alterations (see Inventory and Monitoring

below).

Distribution and Connectivity Trends

At the turn of the 1900’s black-tailed prairie dogs occupied more than 40 million nearly

continuous hectares (Merriam 1902 as cited in Van Pelt 1999), and their range included portions

of eleven States, Canada, and Mexico. Less than 1% of that area (< 324,000 ha) was occupied as


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of 1998 (VanPutten and Miller 1999). Despite the loss of habitat, C. ludovicianus are still widely

distributed over their original range; although, they now occur in small, fragmented, isolated

patches (Miller et al. 2000; USFWS 2004b). Arizona is the only state that the black-tailed prairie

dog has been totally extirpated from its former range (Mulhern and Knowles 1995). Reduction in

connectivity between colonies has probably had minor impacts on genetic diversity (see Roach et

al. 2001, Dobson et al. 2004), but major impacts on recolonization success after serious population

reductions (i.e., after plague or eradication efforts; see below).

Range contractions have been most evident in Arizona (now extirpated), western New Mexico,

and western Texas through conversion of grasslands to desert shrub lands and in the eastern

portion of C. ludovicianus range in Kansas, Nebraska, Okalahoma, South Dakota, and Texas

through cropland development (USFWS 2004b). Most of the range reduction from agricultural

development occurred in the early- to mid-1900s, and is a minimal threat today (see Extrinsic

Threats).

The Interstate Black-tailed Prairie Dog Management Team plan states that Wyoming has a

fraction (~ 0.01%) of the historical range currently occupied by active colonies (Luce 2003). In

Wyoming, there is very little land under cultivation (< 5%), so the levels of land conversion

observed in other parts of this species range have not impacted the species as severely.

Competition with livestock ranching, and the control efforts that result (see Below), remains the

main threat to further loss of species range. Landowner incentive programs may promote the use

of some lands, currently used intensively for grazing, for prairie dog habitat.

Extrinsic Threats

The cause of C. ludovicianus population declines in the past century can be attributed to 1)

intensive eradication programs, 2) agricultural conversion of rangelands, 3) sylvatic plague, 4)


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urbanization, and 5) recreational shooting. (Wuerthner 1997; Van Pelt 1999). The synergy of

these threats may reduce populations drastically. The following section will address these issues.

oisoning and shooting of prairie dogs by ranchers, and agricultural conversion of habitat are

responsible for the majority of C. ludovicianus population decline (Miller et al. 1990, 1994)

Control Programs

Poisoning programs were initiated in the early 1900’s when prairie dogs were first deemed an

agricultural threat by Merriam (1902 as cited in Van Pelt 1999), with accusations that prairie dogs

compete with domestic livestock for forage (Hoogland 1996). Both small-scale (i.e., trapping and

drowning) and large-scale (i.e., poisoning and fumigation) eradication programs were used (Barko

1997). Since federal eradication programs were initiated in 1915, many federal land and wildlife

management agencies, as well as state agencies, have been responsible for the extirpation of

prairie dogs from millions of hectares (Anderson et al. 1986, Mulhern and Knowles 1995). In

fact, it is thought that such poison eradication programs were responsible for the extirpation of C.

ludovicianus in Arizona (see AGFD 1988). Despite modern evidence about grazing relationships

(Coppock et al. 1983b, Uresk and Bjugstad 1983, Uresk 1984), and demonstration of the

economic inefficacy of poisoning (Miller et al. 1996), this practice has continued into the 1990’s

with state and federal mandates. Though federal and state agencies have slowed poisoning in 1999

(WYGF 2001), private land owners are still permitted to exterminate prairie dogs from their lands.

However, many states, including Wyoming, are developing incentive programs for private

landowners to keep prairie dogs on their lands (WYGF 2001). Shooting also occurs for population

control across the range of all 5 species in the U.S. (Mulhern and Knowles 1995). The USFWS

(2004b) no longer consider control programs a threat to the persistence of C. ludovicianus

populations across its range; chemical control programs and synergistic effects were considered a

moderate imminent threat.


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Recreational Shooting

Little is known about recreational shooting affects on C. ludovicianus populations; however, it

is suggested that recreational shooting would only limit, not extirpate populations (Vosburgh and

Irby 1998). Fox and Knowles (1995 in Mulhern and Knowles 1995) state that it would require

one recreational day of shooting for every 6ha of prairie dogs to adversely affect populations. In

addition, the USFWS (2004b) have found recreational shooting only a low, imminent threat, since

it has been recognized that populations are capable of recovering from such adverse impacts.

However, in some states, interest in recreational shooting has increased. Some States with large

amounts of public land are experiencing increased shooting pressures on prairie dogs (USFWS

2004b). For example, in Wyoming, an increase in requests from the public as to where to shoot

prairie dogs has been noted by Wyoming Game and Fish Department, Wyoming Department of

Agriculture, and local Chambers of Commerce. This increased interest in prairie dog shooting,

both locally and out-of-state has raised some concern that recreational shooting may become a

significant contributor to C. ludovicianus population declines in Wyoming (WBTPDWG 2001).

States concerned with increased recreational shooting are beginning to implement regulations to

better monitor and control this activity (USFWS 2004b). Recently, Thunder Basin National

Grassland has implemented a no shooting policy on 45,000 acres of prairie dog habitat in

northeastern Wyoming (USDA 2004). This ban is one of the first of its kind on public lands.

Other States, such as Arizona, Colorado, Montana, and South Dakota have also begun to restrict

hunting on C. ludovicianus by limiting seasons and/or closing public lands. Still other States have

begun to require hunting permits for public lands (Luce 2003). Shooting restrictions extended by

some states on black-tails are a positive step; however, some researchers are concerned that it will

cause a shift of shooting to the other species of Cynomys (VanPutten and Miller 1999).


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Habitat Alterations

Reductions in C. ludovicianus habitat have occurred across its historical range, as a result of

urban development and conversion of rangelands for agricultural purposes. Historically, it was

conversion of short- and mixed-grass prairie for agriculture that was the major cause of

populations decline, specifically in the eastern range of C. ludovicianus (Graul 1980, Dinsmore

1983). However, conversion of habitat from agricultural development is no longer deemed a

threat to the persistence of C. ludovicianus (USFWS 2004b), since most of the arable land has

already been converted (Mulhern and Knowles 1995). This reduced threat is in part a result of

research by Sidle et al. (2001) that noted that vast areas of suitable habitat for colonization and

expansion of this species still remain, as well as reports that estimate hundreds of millions of acres

of potential habitat still remain intact (see USFWS 2004b and Table 1). Along the Front Range in

Colorado, urbanization is considered one of the greatest threats to habitat loss (CBOS 1996;

CDOW 2003). The USFWS (2004b) recognize that this may be a factor in habitat loss along the

Front Range, but does not feel urbanization would present a substantial threat to C. ludovicianus

across its entire range. In Wyoming, the population of Crook, Cambell, Johnson, Sheridan, and

Laramie Counties has increased >10%, Weston, Converse, Platte, and Goshen Counties has

increased by <10%, and the only county within C. ludovicianus range that has decreased, is

Niobrara County (Miller 2001). The associated urban development with the population growth

may become more of a threat to C. ludovicianus populations than has been present in the past.

Losses in extent and connectivity of native short- and mixed-grassland ecosystems of the Great

Plains of North America have been drastic. Historically, C. ludovicianus range was continuous

and covered >40 million hectares; however, over the past century, this habitat has been

fragmented and reduced to less than 600,000ha (Miller and Cully 2001). Fragmentation of

grasslands has occurred from such activities as agriculture, urban development (and its associated


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roads), and oil and gas development (Van Pelt 1999). As a result of this fragmented landscape,

colonies have been isolated from one another, disrupting gene flow and successful distribution of

dispersing males from their natal colony (Roach et al. 2001). Although habitat has been

fragmented and some colonies isolated, it does not appear that this creates a great loss in genetic

diversity (see Dobson et al. 2004). On the other hand, if populations are isolated from potential

emigrating individuals, and the population within that colony is eliminated, it could become

locally extinct. The USFWS (2004a) suggest that isolation of colonies may present a defense

against the spread of plague, leaving some remnant populations unaffected and therefore do not

deem habitat fragmentation an imminent threat to C. ludovicianus populations. In Wyoming, oil

and gas development and population increase may become an issue, since suitable C. ludovicianus

habitat is being developed (see Figure 8).

Although habitat loss appears to be a large threat to C. ludovicianus populations, it does appear

that this species can adapt to various changes in their habitat. For example, Sidle et al. (2001)

documented active C. ludovicianus colonies on small patches of grassland surrounded by

agricultural development and near housing developments in Nebraska, and in the vicinity of roads

and other developments in Wyoming.

Disease

Sylvatic plague (Yersinia pestis; known as Bubonic plague in humans) is an exotic bacterial

disease that first entered the United States just before the turn of the century (Culley 1989). It was

first discovered in the 1940’s in Texas (Cully et al. 1997). This disease has profound impacts on

populations of prairie dogs (mortality ≥ 99%), which have little to no immunity. The plague can

be especially devastating for isolated populations (see Wuerthner 1997). However, isolation of

populations as a result of habitat fragmentation may be beneficial in preventing the spread of

plague throughout entire metapopulations (see Habitat Alteration above). Plague not only has


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serious immediate effects, but long term population and demographic effects as well when coupled

with shooting and poisoning. In fact the demographic changes imposed by such activities may

place the species in an “extinction vortex” that the species may not recover from (Gilpin 1999).

Populations west of the Dakotas commonly experience epizootics every 5-7 years (Culley, pers.

comm.) and these outbreaks may hold the population level at about 40% of what it was before the

epizootic (Knowles 1987).

Plague continues to be a threat to C. ludovicianus populations in Wyoming. Nearly all

Wyoming populations of white and black-tailed prairie dogs have witnessed declines due to

plague outbreaks since the 1930’s (WBTPDWG 2001). It is suspected that the plague is

responsible for population declines in Wyoming (see Abundance Trends). Important locations of

extensive black-tailed colonies, such as Thunder Basin National Grassland, have experienced

losses of up to 70% of the total active acreage due to plague epizootics (T. Byer, personal

communication).

The movement and maintenance of plague is not well understood (Anderson and Williams

1997) and needs further research. However, it has not yet expanded to cover the species national

range. The occurrence of Y. pestis is generally west of the Dakotas; however, new reports indicate

steady eastward movement in the southern part of the range, into Kansas (Cully et al. 2000). It is

thought that the disjunctive and patchy distribution of C. ludovicianus populations throughout its

range has prevented the devastating affects of plague on populations (WBTPDWG 2001).

Although the USFWS (2004b) considers plague the most important factor influencing black-

tailed prairie dogs, they still only view plague as a moderate, imminent threat. They base their

findings on the following information: 1) high exposure doses of plague bacilli may be necessary

for disease contraction in some individuals, 2) limited immune response has been observed in


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some individuals, 3) a population dynamic may have developed in low-density isolated

populations that contributes to the persistence of these populations, 4) the apparent ability of some

sites to recover pre-plague levels after a plague epizootic, and 5) approximately one-third of the

species’ historic range has not been affected by plague.

Other

Predation of prairie dogs by coyotes (Canis latrans), badgers (Taxidea taxus), black footed

ferrets (Mustela nigripes), bobcats (Lynx rufus), rattlesnakes (Crotalis spp), bullsnakes (Piuophis

melanoleucus), golden eagles (Aquila chrysaetos), prairie falcons (Falco mexicanus), and accipiter

and buteo hawks (Accipiter sp. and Buteo sp.) has occurred for as long as these species have

inhabited the Great Plains. It is unlikely that these predators present a significant population threat

to the species on their own (Hoogland 1981, 1996; WBTPDWG 2001). In addition, coloniality

and antipredator calls offer a great predator detection system to minimize predation loss (Linner

2001). However, human predation in the form of recreational shooting may be an important

adverse factor (see Recreational Shooting above), since recreational hunting can remove many

individuals each day and change the demographic structure of metapopulations (Knowles 1987).

Invasive plant and animal species (other than plague, discussed below) do not appear to be a

problem affecting prairie dog abundance or distribution.

Intrinsic Vulnerability

Habitat Specificity and Fidelity

Black-tailed prairie dogs occupy short- and mixed-grass prairie ecosystems, which can vary

with respect to plant species composition, soil type, and topography (see Habitat). However, due

to the colonial nature of C. ludovicianus, high fidelity for their habitat, once selected, is

demonstrated. A loss of utilized habitat may cause populations to decrease.


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Territoriality and Area Requirements

Within colonies, family groups (coteries) are extremely territorial defending their territory

from other coteries (Hoogland 1995). Coterie’s territories usually occupy about one-third of a

hectare (Hoogland 1996); however, coteries occupying areas as large 1.01 hectares have been

documented (Hoogland 1995). Since individuals of a coterie obtain 99% of their food and other

resources within their territory, size and habitat quality is important (Hoogland 1995). Hof et al.

(2004) estimated that one hectare could successfully maintain 18.4 individual prairie dogs.

However, this number may be high for Wyoming. For example, when compared with other states

within C. ludovicianus range, it appears that populations within Wyoming require larger tracts of

land per colony, averaging 13 – 764 hectares per colony (see Clark et al. 1982). Fragmentation

that reduces habitat availability may be detrimental to the populations.

Susceptibility to Disease

Although coloniality is thought to benefit communities of C. ludovicianus (i.e., predator

detection), coloniality also promotes the spread of disease, which could significantly suppress

local populations (Linner 2001). For example, sylvatic plague (Yersinia pestis), an exotic

bacterial disease that first entered the United States just before the turn of the century (Culley

1989), has profound impacts on populations of C. ludovicianus (mortality ≥ 99%), which have no

immunity. Plague can spread across whole C. ludovicianus complexes in just a few years (e.g.,

Anderson and Williams 1997, Cully and Williams 2001). Plague not only has serious immediate

effects (mortality), but long term population and demographic effects, such as local extirpation of

colonies, reduced colony size, increased variance in local population sizes, and increased distances

between colonies. The latter can reduce the effectiveness of dispersal among colonies to

recolonize after local extinction and increase the probability of extinction for entire complexes

(Culley and Williams 2001). The effects of plague on populations are even more devastating


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when coupled with shooting and poisoning. In fact the demographic changes imposed by such

activities may place the species in an “extinction vortex” that C. ludovicianus may not recover

from (Gilpin 1999). Populations west of the Dakotas commonly experience epizootics every 5-7

years (Culley, pers. comm.) and these outbreaks may hold the population level at about 40% of

what it was before the epizootic (Knowles 1987).

In Wyoming plague continues to be a threat to black-tail populations. The disease has not yet

expanded to cover the species national range, but nearly all Wyoming populations of white and

black-tailed prairie dogs have witnessed declines due to plague outbreaks. Important locations of

extensive black tailed colonies, such as Thunder Basin National Grassland, have experienced

losses of up to 70% of the total active acreage due to plague epizootics (T. Byer, personal

communication). The movement and maintenance of plague is not well understood (Anderson

and Williams 1997) and needs further research. The occurrence of Y. pestis is generally west of the

Dakotas. However, new reports indicate steady eastward movement in the southern part of the

range, into Kansas (Cully et al. 2000).

Dispersal Capability

Cynomys ludovicianus are capable of dispersing from natal colonies as far as 5km; however,

C. ludovicianus will rarely disperse beyond the natal colony due to predatory risk without the

warning “predator” calls of conspecifics (see Dispersal). In fact, it is estimated that survival rate

decreases by 40% for each 5km dispersal distance (Hof et al. 2002). Roach et al. (2001) showed

that prairie dogs within a 264km2 area of the Central Plains Experimental Range and Pawnee

National Grasslands in northern Colorado had a dispersal rate among established colonies of about

39%. It is largely unknown how often C. ludovicianus disperse to previously unoccupied sites,

but is thought to be rare. Garret and Franklin (1988) demonstrated that dispersal rates increased as

available food resources decreased. In highly fragmented colonies (i.e., urban and agricultural


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development), dispersal capability may be limited. The inability to disperse may create areas of

high population density, increased competition for resources, and result in decreased habitat

quality, which may lead to population decline and increased inbreeding (see Johnson and Collinge

2004). Other factors that could affect the dispersal of C. ludovicianus is the availability of high-

visibility corridors or attractants such as chirping of other prairie dogs (Hof et al. 2002).

Reproductive Capacity

Hoogland (2001) demonstrated that C. ludovicianus have lower intrinsic rates of increase and

are consequently more vulnerable to colony extinction than most other rodents. Five factors are

responsible for this slow reproduction: 1) survivorship is <60% in the first year, 2) only one

litter/year is produced, even under optimal conditions, 3) only 6% of males copulate as yearlings,

4) the probability of weaning a litter each year is only 43%, and 5) mean litter size at first juvenile

emergence is usually 3.08. In addition, females may breed in their first year, but generally do not

breed until their second year. On top of that, free-ranging species may only live three – to four

years (Hoogland 1995). As a result, C. ludovicianus are slow to recover from population crashes

such as a plague epizootic and must rely on recolonization from other colonies to recover or

reestablish (see Metapopulation Dyamics). Cincotta et al. (1987) suggest that dispersing prairie

dogs do not reproduce during their first year in a new colony. This may also play a factor in

reproductive capacity. In spite of these facts, some researchers have suggested that C.

ludovicianus are capable of rapid population increases subsequent to substantial reductions (see

USFWS 2004b).

Protected Areas

In some areas of the species range, prairie dogs are protected from anthropogenically induced

effects on national monuments, wildlife refuges and specially protected areas of federally

managed lands. One such area is a shooting restricted zone in Thunder Basin National Grassland,


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Wyoming which provides approximately 20,000 acres. However, in contrast to the species range

as a whole, the amount of protected area present is a very small percentage. The lack of large

tracts of protected prairie dog range has caused some concern among managers due to the inter-

colony dispersal that must occur to ensure long term survival of colony complexes that necessarily

span large areas of land. As conservation plans are formulated and adopted by various

management agencies, the amount of protected area is expected to increase. However, the extent

of protections afforded and the extent of land thus impacted is currently uncertain.

Population Viability Analyses (PVAs)

For purposes of intensive management a suitable PVA has not been developed (Luce 2001).

However, an interactive, web-based PVA model has been completed by Michael Gilpin at San

Diego State University (SDSU) and contracted with the USFWS is available to view and use at

http://gemini.msu.montana.edu/ ~mgilpin.prairie_dog.html. This PVA gives an excellent

overview of many aspects of prairie dog management including an introduction to the

metapopulation structure of black-tails. The interactive “applets” allow the user to manipulate

varying conditions that effect population size and persistence such as plague and shooting.

Conservation Action

Existing Conservation Plans

The eleven states within the range of C. ludovicianus began a multi-state conservation effort in

1998 to promote conservation and avoid the federal listing of C. ludovicianus. The Black-Tailed

Conservation Assessment and Strategy (CA&S) was developed in 1999. The purpose of the

CA&S is to manage, maintain, and enhance habitat and populations of C. ludovicianus across its

historic range and reduce the number of threats impacting their viability through the cooperation

of private, tribal, federal, and state landowners. It provides actions, opportunities, and incentives


Page 34 of 62

for interested parties to become involved with conservation efforts of C. ludovicianus, as well as

management suggestions such as eliminating mandatory control, regulating seasons or possession

limits, maintaining and conserving required habitat and ecosystems, and establishing core

populations on public lands to provide animals for dispersal to uninhabited areas or individuals for

recolonization (Van Pelt 1999). In 2003 a Multi-State Conservation Plan (MSCP) was completed

as an addendum to the CA&S to provide guidelines under which adaptive management plans will

be developed by individual states and their respective working groups representing all

stakeholders viewpoints (see Luce 2003). Currently ten of the eleven states in the range of C.

ludovicianus have developed or drafted state prairie dog management plans: Interagency

Management Plan for Black-Tailed Prairie Dogs in Arizona (Van Pelt et al. 2001), Conservation

Plan for Grassland Species in Colorado (CDOW 2003), Kansas Black-Tailed Prairie Dog

Management Plan (Kansas Department of Wildlife and Parks 2002), A Species Conservation Plan

for the Black- and White-Tailed Prairie Dogs in Montana (Knowles 1999), New Mexico, North

Dakota, Oklahoma (see Luce 2003), South Dakota Black-tailed Prairie Dog Management Plan

(Cooper and Gabriel 2005), Texas Black-Tailed Prairie Dog Conservation and Management Plan

(TBTPDWG 2004), Draft Wyoming Black-Tailed Prairie Dog Management Plan (Kruckenberg et

al. 2001; WBPDWG 2001). Together, the CA&S, the MSCP, and the eleven state management

plans hope to remove enough threats to C. ludovicianus in order to curtail needs for listing under

the ESA while allowing for more flexible management practices. The following target objectives

were created in the MSCP to help achieve this goal:

1. Maintain at least the currently occupied acreage of black-tailed prairie dogs in the U.S. (see

Table 1).

2. Increase to at least 1,693,695 acres of occupied black-tailed prairie dog acreage in the U.S.

by 2011.


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3. Maintain at least the current black-tailed prairie dog occupied acreage in the two

complexes greater than 5,000 acres that now occur on the adjacent to Conata Basin-Buffalo

Gap National Grassland, South Dakota, and Thunder Basin National Grassland, Wyoming.

4. Develop and maintain a minimum of 9 additional complexes greater than 5,000 acres (with

each state managing or contributing to at least one complex greater than 5,000 acres) by

2011.

5. Maintain at least 10% of total occupied acreage in colonies or complexes greater than 1000

acres by 2011.

6. Maintain distribution over at least 75% of the counties in the historic range or at least 75%

of the historic geographic distribution.

The issue of recreational shooting is slowly being addressed over much of the range of black-

tailed prairie dogs. Licenses that were previously un-necessary to shoot C. ludovicianus are now

required in all states except Montana and Wyoming. However new management ideas have been

presented by the Wyoming citizen’s working group. These ideas include: temporary closing of

shooting if population numbers decline to 15% above objective (200,000 acres) from current

levels, develop management units/licensing protocols, and work with the public to develop

management strategies (WYGF 2001). In Wyoming, shooting restrictions were enacted on focal

populations in Thunder Basin National Grassland during the spring of 2001 to allow populations

to expand in anticipation of black-footed ferret reintroduction. Future yearlong closures are

proposed by the Wyoming Game and Fish Department (WYGF) for areas considered as important

focal regions for conservation of the species (WYGF 2001). Wyoming G&F has begun to develop

a memorandum of understanding (MOU) between agricultural, weed and pest, and wildlife

commissions to limit poison distribution and to develop land owner incentives for keeping prairie

dogs on their lands (WYGF 2001).

The National Forest Service (NFS) has also adopted management strategies to conserve C.

ludovicianus on NFS lands (i.e., Thunder Basin National Grassland, Dakota Prairie Grasslands,


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and Nebraska National Forest Land) which are occupied (>70%) by C. ludovicianus populations

(USDA 2004). These strategies include guidance and directions for the use of rodenticides,

landownership adjustment, vegetation management, livestock grazing, prairie dog

shooting/hunting, and other management options to either expand or limit growth of prairie dog

populations and colonies on NFS lands (see USFWS 2004c).

Conservation Elements

Although C. ludovicianus has not been listed as threatened or endangered by the Endangered

Species Act, the long-term decline in abundance and distribution across its historic range suggests

that there is a need to undertake conservation actions to mitigate such a decline while viable

populations still exist. This need is compounded by the fact that the C. ludovicianus provides

habitat and a food source for a variety of wildlife species, including the endangered black-footed

ferret (see Community Ecology). In Wyoming, conservation efforts should be attentive, since far

less habitat has been lost in Wyoming than in most other states within the species’ distribution

(WBTPDWG 2001) and only 79% of suitable habitat is currently occupied by C. ludovicianus in

Wyoming (see Table 1). Five main conservation elements should be addressed for C.

ludovicianus conservation management in Wyoming. For more rangewide suggestions, please

review Van Pelt (1999). Specific approaches that have been proposed to address these

conservation elements are provided in the following section.

1. Habitat Conservation: Reduce conversion of land to uses not compatible with local

persistence of C. ludovicianus and minimize impacts of semi-compatible uses, including

livestock grazing and resource extraction.

2. Disease Control: The spread of disease (specifically sylvatic plague) among C.

ludovicianus should be investigated and management should seek to minimize its

impacts on prairie dog complexes.


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3. Shooting and Extermination Control: Unless strictly controlled, recreational shooting

and pest control efforts aimed at killing C. ludovicianus are not compatible with healthy

populations.

4. Inventory and Monitor Populations: Current monitoring efforts are insufficient to

generate reliable and comparable trend information and are therefore inadequate to track

the future of C. ludovicianus populations. A thorough and consistent methodology must

be applied in Wyoming and across its range, as discussed in the Inventory and

Monitoring section below.

5. Public Education: In order to apply the above mentioned conservation elements to

successful management programs in Wyoming, public attitudes toward prairie dogs need

to change. Literature citing the importance of C. ludovicianus to rangeland habitat and

its associated species need to be easily acquired and come in a variety of materials (i.e.,

brochures, videos, information boards, etc.).

Acting on Conservation Elements

There are many state citizens’ working groups that have developed or are currently drafting

conservation plans for C. ludovicianus and provide suggestions for management practices for C.

ludovicianus. In addition, research published that focused specifically on C. ludovicianus has also

provided management suggestions that may provide the best opportunity to conserve preferred

habitat and viable populations of C. ludovicianus.

1. Habitat Conservation: It appears that conservation efforts to protect lands currently

occupied (and adjacent) by C. ludovicianus is beneficial for maintaining or increasing

abundance (see Table 2). Identifying tracts of lands occupied by C. ludovicianus

(especially those >5,000 acres; see Van Pelt 1999) should be conducted through

coordinated efforts of all federal agencies to maximize the conservation potential and

preserve, if not increase, occupied habitat. In Wyoming, this objective is no less than

200,000 acres (WBTPDWG 2001). Maintaining large tracts of land will provide enough

acreage and C. ludovicianus population to support reintroduced and recovering black-

footed ferret populations, as well as other associated species (Luce 2003). Lomolino et al.

(2003) suggest a mixed strategy for preserving habitat: maintain or develop widely


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distributed large and small complexes (connected for dispersal purposes; Roach et al.

2001), and retain small and large isolated colonies throughout the range to help create

barriers to prevent spread of the plague and potential eradication of metapopulations.

Create buffers (~75 feet) around protected areas to provide area for expansion. In cases

where adjacent land is not compatible with prairie dog colonies (i.e., hay or crop fields),

create barriers beyond the buffers (i.e., tall grasses) to prevent establishment and/or

foraging in these sites (CBOS 1996). Provide incentives for private landowners to

voluntarily maintain prairie dog colonies on portions of their lands, since conserving C.

ludovicianus habitat is not fully possible without the assistance of private landowners. In

Wyoming, this is important, since private land constitutes a large percentage of total prairie

dog habitat (WBTPDWG 2001). The multi-state conservation plan outlines a possible

incentive program that could be pursued by individual states under such authorities as the

Conservation Title of the Farm bill, Conservation Reserve Program, or Grasslands Reserve

Program in Appendix E (Luce 2003). In addition, impacts that could adversely affect

established or potential C. ludovicianus through urban, oil, and/or gas development should

be minimized or eliminated. The following are suggestions to mitigate habitat alteration:

• Identify suitable habitat and current colonies before proposed oil and gas

exploration and urban development sites are initiated.

• Determine local population densities, quality of habitat, spatial distribution of

colonies and habitats (for connectivity and dispersal purposes), and how activities

(i.e., drilling) may impact these factors.

• Locate roads outside areas of current, recent, or potential prairie dog habitats

identified.

• Place restrictions on vehicle traffic (for mining operations) during the breeding

season and dispersal (March through August) to help minimize stress and possible

increased infanticide.

2. Disease Control: Currently there are no known vaccines to immunize C. ludovicianus

against threat of the plague. However, steps can be taken to mitigate plague impacts. The

multi-state conservation plan (Appendix D; Luce 2003) provides a plague protocol for all

eleven states to initiate. It includes a plague monitoring protocol, procedures for visual

evaluation of prairie dog colonies for plague, field procedures for collecting and handling


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carcasses as diagnostic specimens, and procedures for swabbing rodent burrows. It is

important to identify colonies in which the plague affected populations, and try to isolate

these colonies from other complexes to stop the spread of the disease. In this case,

colonies should be greater than 3km from their nearest neighbor colonies (Cully and

Williams 2001). In addition, implementing the suggested mixed-strategy complex design

(connected complexes with isolated colonies) will help reduce disease transmission, while

maintaining some vital corridors to facilitate repopulation of eradicated populations (see

Lomolino et al. 2003).

3. Shooting and Extermination Control: Unless strictly controlled, recreational shooting

may not be compatible with healthy populations of prairie dogs, altering behavior and

reproductive success, especially if this activity increases (Reeve, personal communication;

Vosburgh and Irby 1998; USFWS 2004b). Further, unlike some threats (e.g., disease) it is

well under the control of land managers. Optimally, shooting should be eliminated,

particularly on otherwise impacted towns (i.e., large plague epidemics). During the past

few years, several states have established better regulations (i.e., closures and season

restrictions) that allow for management of recreation shooting; as well, they have changed

the status of species from pest to a designation that recognizes the need for management.

However, inn Kansas, North Dakota, and Wyoming, C. ludovicianus is still considered a

pest and controlled as such (Luce 2003). The following are some restrictions that could

help regulate recreational shooting of C. ludovicianus to assist in the conservation and

protection of the species (Luce 2003):

• Seasonal closures to all shooting during whelping and dependent young period

(March 1 to June 30).

• Require permits specific to designated areas and limit take.

• Collect data on harvest (i.e., age and sex of animals harvested), hunter days per

county, and hunter days/harvested animal through annual field checks and mail

surveys, allowing State Wildlife Agencies to accurately quantify annual harvest.

In Wyoming, C. ludovicianus is considered a pest and management is overseen by the

Wyoming Weed and Pest Council, Board of Agriculture, and Wyoming Game and Fish

Commission. Currently a memorandum of understanding is being drafted in which these

agencies agree to limit the distribution of poisons and their participation in poisoning


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efforts when survey results indicate conservation plan objectives (i.e., acreage) is in

jeopardy. Temporary restrictions on agency poisoning or cooperation with landowners

using poison or other control methods should be implemented at local levels when

necessary (i.e., poisoning compounding impacts by other threats to populations;

WBTPDWG 2001).

4. Inventory and Monitor Populations: Conducting a baseline, state wide inventory of the

number of acres contained within is crucial for long term population monitoring of this

species. This information will allow management agencies to develop population targets,

identify important population centers throughout the state, and give a measurable level of

increase or decrease in population size under new management regimes. Sidle et al. (2001)

present new estimates of prairie dog abundance in four states that are critically important to

conservation of C. ludovicianus, and present a new aerial survey technique for abundance

estimation that is replicable, includes estimates of precision, and does not require trespass

permission from private landowners (Miller and Culley 2001; Sidle et al. 2001). It is

important that methods range-wide are compatible with each other for comparison. The

following strategies were outlined in the Wyoming conservation plan (WBTPDWG 2001):

• Develop a cooperative effort to fund and conduct research and regularly scheduled

inventories.

• Continue to develop remote census techniques (i.e., Sidle et al. 2001).

• Evaluate aerial transect techniques to identify the approach and sampling design

best suited for Wyoming (see Appendix IX).

• Conduct selected techniques in areas where ground surveys are being conducted

(e.g., Thunder Basin National Grasslands) and evaluate accuracy and precision of

techniques.

• Coordinate with adjacent states to assure that results will be comparable.

• Select a reliable method, and initiate inventories to document occupied habitat

(initiated July 2002).

• Conduct monitoring survey at three-year intervals from 2002.

5. Public Education: Lamb et al. (2001) conducted an eleven state survey within short-grass

prairie systems regarding the public’s attitude and knowledge of black-tailed prairie dogs.


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Overall, the public did not highly regard C. ludovicianus and did not consider conservation

of C. ludovicianus of great importance when compared with larger environmental issues,

such as global warming. People will only value grasslands and prairie dogs to the degree

that they understand them. Therefore, education of prairie dog may increase the desire to

manage prairie dogs, especially since the anti-prairie dog attitude is still pervasive in

federal, state, and public views (Knowles 1999; Lamb et al. 2001). Education and outreach

materials should cover many topics including but not limited to prairie dog management,

prairie dog ecology, plague, and effects of prairie dogs on rangelands and agricultural land.

It is important that outreach materials and education programs are factual and represent

interests of all stakeholder groups (TBTPDWG 2004). Examples of educational

techniques could be: in-school presentation, nature hikes, slide presentations, brochures,

and interpretative displays (CBOS 1996).

Habitat Preservation and Restoration

Habitat fragmentation and transformation of the Great Plains grasslands biome has been the

most extensive of any in North America. This habitat alteration has impacted the continuity of

large, historic habitat needed to establish extensive networks of prairie dog colonies and maintain

inter-colony genetic diversity. Clearly, this is an important component of future conservation

efforts. Programs that create, protect, and restore suitable habitat and connectivity offer some

promise to provide habitat for successful prairie dog colonies/populations.

Roe and Roe (2003) offer guidelines to be used when selecting habitat for C. ludovicianus

relocation efforts, which could be used for habitat restoration/preservation efforts (see Table 3).

The guidelines present environmental parameters specific to soils, vegetation height, cover, and

palatable species, slope, and optimal proximity to other established prairie dog colonies. In

addition, Lomolino and Smith (2003b) and Lomolino et al. (2003) recommend conserving a

network of native prairie reserves strategically located across the historic range of C. ludovicianus.

They suggest that the network be comprised of “clusters” of large (presumably >10 ha, but size is


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not directly specified by the authors) towns, as well as large, isolated towns. The latter will be less

likely to be infected or serve as a source for spread of the plague. Large towns will also be more

likely support populations of C. ludovicianus and other associated vertebrates into the future

(Lomolino and Smith 2001), buffering adverse effects from various extrinsic extinction forces

(i.e., land conversion, expansion of roads, habitat reduction and fragmentation, and plague).

When restoring habitat for reintroduction of C. ludovicianus, whether to provide a food-base

for black-footed ferrets, or to reestablish C. ludovicianus in their historic range, long-term

planning is needed, as well as sufficient 1) area of land and habitat, 2) pre-introduction ecological

studies and site preparation, 3) breeding individuals to make a reproducing population, 4)

protection, and 5) monitoring and follow up studies (AGFD 2004).

Information Needs

Identifying specific information needs will help management agencies to formulate appropriate

conservation strategies by targeting key areas needed for effective conservation of the species.

The following list briefly notes some of the key information needed to develop sound C.

ludovicianus conservation strategies.

1. Inventory/Monitoring: The development of long term monitoring and inventory of

black-tailed prairie dog populations is needed. Without a way to reliably and quantitatively

determine trends in abundance and distribution, managers have no way to assess the status

of C. ludovicianus populations or the effect of management actions on these populations.

Inventories should determine locations and sizes of colonies, land ownership, and presence

of plague. Monitoring of known C. ludovicianus populations will help managers assess the

affects of impacts, such as oil and gas projects, on population trends. Remote sensing and

aerial and ground techniques need to be developed and standardized among agencies to

ensure validity, smooth information flow, and communication (see Sidle et al. 2001).


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2. Disease: Plague continues as one of the most detrimental threats to this species longevity

and healthy population growth. Although some research has investigated the dynamics of

plague in prairie dog colonies, there are still huge questions regarding its prevalence, cycle

of occurrence, and distribution in the natural environment. Managers need to know how

plague spreads between colonies and how it is maintained within colonies. Strategies

allowing managers to predict and mitigate epizootics is very important given the

catastrophic impact this disease has had on prairie dogs; for instance, field trials of

vaccinations or parasite management strategies and/or real-time, large-scale, high-

resolution mapping of epidemics. It is unknown if prairie dogs may one day develop

immunity to the disease or if virulence will stay high.

3. Shooting and Poisoning: Recreational shooting effects have been studied preliminarily

(Knowles 1987, K. Gordon, pers. comm.), but further research is needed to fully

understand the impact of this activity on demographic structure and population dynamics.

Depending on the outcome of ongoing studies, shooting may continue in some areas, but

regulation and monitoring of this activity are keys to controlling its effects as evidenced by

many years of hunting regulation for game species.

4. Ecological Ramifications: More research is needed on the long-term effects of C.

ludovicianus on floral, faunal, and soil communities to determine if they are indeed a

keystone species, and important for the persistence of a variety of species (see Community

Ecology above).


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Tables and Figures

Table 1: Baily Eco-Region habitat model distributions for each state (Native American tribes in

Montana, South Dakota, and North Dakota set acreage objectives independent of states.)

Historic Current Gross Suitable Minimum State Habitat* Habitat Habitat** Habitat*** 10-Yr Objective

AZ 7,047,137 0 7,047 4,594 4,594

CO 27,352,880 631,102 273,529 255,773 255,773

KS 35,835,079 130,521 150,714 148,596 148,596

MT 60,442,757 90,000 297,286

240,3671

240,3671

NE 36,035,433 80,000 146,741 137,254 137,254

ND 11,045,269 20,500 110,453

100,5512

100,5512

NM 39,021,449 60,000 96,661 87,1323 87,132

3

OK 21,606,120 22,000 70,868 68,657 68,657

SD 29,262,553 160,000 218,121 199,4724

199,4724

TX 78,592,452 167,625 310,945 293,129 293,129

WY 22,067,599 125,000 179,072 158,1705

158,1705

Total: 368,308,727 1,486,748 1,861,436 1,693,695 1,693,695

* Refers to total potential habitat encompassed within the range (Hall 1981), not occupied habitat

** Gross habitat = total acreage of primary range x 1% + total acres of peripheral range x .1% (Table 2 and

Figure 3)

*** Suitable habitat = gross habitat minus habitat with >10% slope, or other unsuitability factors (Agricultural

lands were included in suitable habitat if they fit the slope and suitability factors)

1 The acreage objective in the State of Montana’s 2001 Management Plan is 90,000-104,000 acres for non-tribal

lands. The state’s acreage objective will be subject to modification in response to a financial incentives program

for landowners if an incentives program is funded. Separate objectives will be set by individual Native American

tribes.

2 The current acreage objective listed in the North Dakota Management Plan is 33,000 acres, including non-tribal

and tribal lands. The state of North Dakota and the Standing Rock Indian Reservation will determine the target

acreage for each jurisdiction. The state is willing to consider an objective of 100,551 acres on non-tribal lands if a

financial incentives program for private landowners is funded. Tribal lands will have separate acreage objectives.

3 The New Mexico acreage objective is based on a percent increase per year, which would take approximately

10 years to achieve the current acreage objective. If future statewide survey efforts indicate a different acreage

than the estimated minimum current acreage listed, the rate for achievement of the 10-year objective will be

adjusted accordingly.

4 The acreage objective for South Dakota includes 169,551 acres of non-tribal lands and 29,921 acres of tribal

lands (pending final approval of management plan).

5 Wyoming’s draft management plan contains an objective to maintain the current acreage, or 200,000 acres,

which ever is greater.


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Table 2: Overview of C. ludovicianus status throughout its range.

Country State/Province State Status

(May 2004)

Heritage

Rank

BLM Species of

Concern

Population Trend

(USFWS 2004b)

United States

Montana Nongame Wildlife; Pest S3 yes Decreasing

3

Increasing/Stable4,5

North Dakota Nongame Wildlife SU yes Stable?/Decreasing?

South Dakota Game Wildlife; Varmint S4 yes Increasing/Stable4

Wyoming Species of Special Concern S2 yes Decreasing

3

Stable4

Nebraska Nongame Wildlife S4 nr Absent

6

Increasing4

Kansas Wildlife S3 nr Absent

6

Increasing4

Colorado Small Game Species S4 nr Decreasing

1,3

Increasing4,5

New Mexico No Legal Listing S2 no Absent

6

Stable?

Arizona Extirpated; Nongame mammals SX no Extirpated1,2

Oklahoma Species of Special Concern S3 nr Absent

6

Stable?

Texas Nongame Wildlife S3 nr ?

Canada

Saskatchewan Special Concern S2 n/a Stable4

Mexico

Amenazada Threatened n/a n/a Absent

1,2,6

Stable4

Heritage Rank: SU = unknown, SX = extirpated, S2 = imperiled, S3 = vulnerable, S4 = apparently secure

BLM Species of Concern:

yes = the State's BLM office recognizes C. ludovicianus as a Species of Concern

no = the State's BLM office does not recognize C. ludovicianus as a Species of Concern

nr = not reported

Population Trend: 1 = habitat conversion, 2 = control efforts, 3 = plague, 4 = habitat preservation, 5 = recovered, 6 =

absent from historic range, ? = not enough information


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Table 3: Guidelines for C. ludovicianus habitat restoration and preservation. Adapted from Roe

and Roe (2003).

Parameters Description

species

western wheatgrass (Pascopyrum smithii), blue grama (Bouteloua

gracilis), buffalograss (Buchloe dactyloides), sand dropseed (Sporobolus

cryptandrus), cheatgrass (Broums tectorum), sixweeks fescue (Vulpia

octoflora), ring myhly (Muhlenbergia torreyi), sedges (Carex spp.), scarlet

globemallow (Sphaeralcea coccinea), and plains prickly pear (Opuntia

polyacantha).

cover <40% bare ground; shortgrass prairie grasslands 58-70%; …

Vegetation

height <30cm

depth ≥2.0m

Soil type

loamy with little to no gravel; low in clay (<30%); meduim in sand

(~50%); medium to high in silt (>70%) with good drainage.

Slope < 20%; preferably ≤10%

Proximity to

established colonies ≥46m and up to 185-277m


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Figure 1: Photograph of adult and juvenile black-tailed prairie dog, Devils Tower National

Monument, WY, © Steven W. Buskirk


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Figure 2: Drawing of skull morphology of C. ludovicianus, adapted from Hoogland (1981).


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Figure 3: North American range of all prairie dog species from Hall (1981).

1. Black-tailed prairie dog

2. Gunnison’s prairie dog

3. Utah prairie dog

4. White-tailed prairie dog

5. Mexican prairie dog


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Figure 4: Possible distribution of C. ludovicianus based on mixed-grass and short-grass prairie

distribution in eastern Wyoming (map acquired from WYGISC website:

www.wygisc.uwyo.edu).


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Figure 5: Rangewide distribution of the black-tailed prairie dog. Outline is the historic

distribution from Hall (1981) and the shaded portion of the range map is from State surveys.

This map does not include current distribution of populations in Canada and Mexico (acquired

from Luce 2003).


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Figure 6. Loop diagram depicting a) life cycle and b) related matrix model elasticities for female

black-tailed prairie dogs (Cynomys ludovicianus) (courtesy J. Pauli, University of Wyoming).

Pi denotes the probability of surviving to the next age class and Fi denotes the fertility of that

age class. eij denotes the elasticity from age class j to age class i. Although female black-tailed

prairie dogs can reach an age of 9, age classes >6 were excluded in elasticity analyses because

older age classes fail to reproduce. The basic loop diagram was constructed from J.

Hoogland’s 14 year study (1975-1988) of black-tailed prairie dogs in Wind Cave National

Park (Hoogland 1995).

P8 = 0.267 P7 = 0.257 P6 = 0.447 P5 = 0.587 P4 = 0.694 P3 = 0.768 P2 = 0.777 P1 = 0.543

F6 = 0.447

F5 = 0.868

F4 = 1.36

F3 = 1.49

F2 = 1.29

1 2 3 4 5 6 7 8 9

F1 = 0.125

e13 = 0.184

e15 = 0.023

e65 = 0.004 e54 = 0.019 e43 = 0.056 e32 = 0.105 e21 = 0.152

e16 = 0.004

e14 = 0.080

e12 = 0.337

1 2 3 4 5 6


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Figure 7: Map of Natural Heritage Ranks for the black-tailed prairie dog (NatureServe 2004).


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Figure 8: Existing oil and gas developments in Wyoming (Knick et al. 2003, p. 619). Note the amount of development in the northeast

section of Wyoming, where the largest populations (acreage) of C. ludovicianus have been reported.


Page 55 of 62

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